Multi-point forming utilising novel elastic cushion designs

Tolipov, Abror (2019). Multi-point forming utilising novel elastic cushion designs. University of Birmingham. Ph.D.

Text - Accepted Version
Available under License All rights reserved.

Download (9MB) | Preview


Currently, there is an increased need for flexible manufacturing methods, which can meet the rapidly changing customer requirements. Reconfigurable dyes can be readily changed to create several shapes with a flexible sheet metal forming technique, which is known as Multi-point forming (MPF). While MPF methods are comprised of unique height-adjustable punches, the overall process has a few geometrical defects.

These include wrinkling, maximum deviation along with thickness variation. Wrinkling may occur due to the discrete punch elements, which may result in defective products. Maximum deviation is a measure of the geometrical accuracy where the deviation from the target shape is measured. It takes place between the formed part and the target shape. Thickness variation is also a representation of the quality of the formed part. Elastic cushions can be inserted amid the multi-point die and the metal sheet to avoid such issues.

Earlier works have focused on optimising the process parameters, such as cushion thickness, the coefficient of friction, radius of curvature of the workpiece and pin size. The MPF process makes use of a matrix of multi-point pins, which assist in the creation of the die surface. However, very little attempts were made to develop and modify the process to eliminate the geometrical defects. This thesis is aimed on investigating two different optimisation processes; new mesh-type elastic cushion and hole-type elastic punch through experimental work and numerical simulations.

In this work, an MPF stamping process utilising a new model mesh-type elastic cushion was studied along with exploring about its influence on wrinkling, maximum deviation, thickness variation and the forming force. This research aims to investigate the effect of the hole types (circular and square) and sizes of the new mesh-type cushion.
This was done as using holes on a sheet is a better idea than using a pure solid, where holes facilitate the formability process. ABAQUS/Explicit FE software and response surface method are used in this investigation to explore the influence of the process variables on wrinkling, maximum deviation, thickness variation, and forming force. Achieved results were matched with the outcomes of the numerical simulations of the MPF for hemispherical shape using a solid cushion. It was revealed that the use of a new model mesh-type cushion could lead to a reduction in wrinkling, maximum deviation, thickness variation and forming load. All numerical results were validated by the experimental results and a fairly reasonable agreement was observed.

In terms of the elastic cushion thickness, it was found that this parameter had no influence on the wrinkling and thickness variation. This study also made use of the Design of Experiments (DoE) approach to derive a process for the relevant process variables, which was then used to pick the most relevant variables. A hole-type elastic punch was developed instead of the MPF punch for reducing the adjustment times and tool costs. It was revealed that this new approach saves half the tool cost and time along with providing the desired results. With the help of the experimental results and numerical simulations, a suitable hole-type (circular) and forming compression (of about 70%) was chosen.

Type of Work: Thesis (Doctorates > Ph.D.)
Award Type: Doctorates > Ph.D.
Licence: All rights reserved
College/Faculty: Colleges (2008 onwards) > College of Engineering & Physical Sciences
School or Department: School of Engineering, Department of Mechanical Engineering
Funders: Other
Other Funders: IDB
Subjects: T Technology > TJ Mechanical engineering and machinery
T Technology > TS Manufactures


Request a Correction Request a Correction
View Item View Item


Downloads per month over past year